Process and materials using z-filter media, and/or, closing flutes of filter media; and, products

ABSTRACT

Approaches to providing z-filter media constructions are provided. Preferred media, filter constructions having such media, and filter systems using such filter constructions are provided. Also, preferred methods of forming filter constructions are provided.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. Ser. No.13/953,188, filed Jul. 29, 2013, which issued as U.S. Pat. No. 8,961,722on Feb. 24, 2015. U.S. Ser. No. 13/953,188 is a continuation of U.S.Ser. No. 13/555,327, filed Jul. 23, 2012, which has issued as U.S. Pat.No. 8,496,774. U.S. Ser. No. 13/555,327 is a continuation of U.S. Ser.No. 10/549,872, filed Sep. 11, 2006, which issued as U.S. Pat. No.8,226,786. U.S. Ser. No. 10/549,872 is a National Stage application ofPCT application PCT/U.S. 2004/007927, which was filed Mar. 17, 2004 witha claim of priority to three U.S. provisional applications as follows:60/455,643 filed Mar. 18, 2003; 60/466,026 filed Apr. 25, 2003; and60/467,521 filed May 2, 2003. A claim of priority is made to each ofU.S. Ser. Nos. 13/953,188; 13/555,327; 10/549,872; PCT/US2004/007927;60/455,643; 60/466,026; and, 60/467,521, to the extent appropriate.Also, each of U.S. Ser. Nos. 13/953,188; 13/555,327; 10/549,872;PCT/US2004/007927; 60/455,643; 60/466,026; and, 60/467,521 isincorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to filter media for use in filteringliquids or gases. The disclosure particularly relates to such media thatutilizes a fluted or corrugated structure, to define filtration flutesor surfaces. Specifically, the disclosure relates to techniques forsealing such flutes in selected portions thereof, and to resultingstructures.

BACKGROUND

Fluid streams, such as air and liquid, carry contaminant materialtherein. In many instances, it is desired to filter some or all of thecontaminant material from the fluid stream. For example, air flowstreams to engines (for example as combustion air) for motorizedvehicles or for power generation equipment, gas streams to gas turbinesystems and air streams to various combustion furnaces, carryparticulate contaminant therein that should be filtered. Also liquidstreams in engine lube systems, hydraulic systems, coolant systems orfuel systems, carry contaminant, that should be filtered. It ispreferred for such systems, that selected contaminant material beremoved from (or have its level reduced in) the fluid. A variety offluid filter (air or liquid filter) arrangements have been developed forcontaminant reduction. In general, however, continued improvements aresought.

SUMMARY

The present disclosure concerns z-filter arrangements, preferablyconstructed utilizing the methods and equipment described herein.

Certain of the disclosed methods involve selective coiling of z-filtermedia. Some preferred applications and methods involve z-filter mediathat uses sealant such as a urethane sealant material, to cause sealingto occur. Preferred applications are described. Also, methods forpreparing preferred filter arrangements are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings, relative dimensions and material thicknessmay be shown exaggerated for clarity.

FIG. 1 is a schematic perspective view of z-filter media.

FIG. 2 is a schematic upstream end view of a filter element utilizingcoiled media according to FIG. 1.

FIG. 3 is a schematic outlet end view of the arrangement depicted inFIG. 1.

FIG. 4 is a schematic enlarged fragmentary view of a portion ofcorrugated media attached to a portion of uncorrugated media, in az-filter construction.

FIG. 5 is an enlarged view of a portion of the media depicted in FIG. 4.

FIG. 6 is a schematic, perspective view of a filter element utilizingfluted filter media having ends sealed in accord with the descriptionsherein.

FIG. 7 is a schematic, perspective view of a second filter elementutilizing fluted filter media constructed in accord with the principlesdescribed herein, and having sealed ends.

FIG. 8 is a schematic view of one embodiment of a system in which aircleaners having elements for filter media of the type described hereinare used.

FIG. 9 is a schematic, perspective view of a filter element utilizingwound fluted filter media having flutes sealed closed in accord with thedescriptions herein, shown having been made without a center board andinclude a framework mounted thereon.

FIG. 10 is a top plan view of the filter element of FIG. 50.

FIG. 11 is a schematic view of a process of forming the filter mediacomponent of the filter element depicted in FIGS. 9 and 10.

FIG. 12 is a top plan view of a filter element analogous to FIG. 10.

FIG. 13 is an enlarged fragmentary view of a portion of FIG. 12.

FIG. 14 is an enlarged fragmentary view of a portion of FIG. 13.

FIG. 15 is a perspective view of a filter element depicted in FIG. 11.

FIG. 16 is a side elevational view of the filter element depicted inFIG. 15.

FIG. 17 is a fragmentary schematic cross-sectional view depicting aportion of the element of FIGS. 12-16.

FIG. 18 is a schematic fragmentary perspective view of the mediadepicted in FIG. 17.

FIG. 19 is a schematic depiction of a process for forming a corrugatedmedia-facing sheet combination, for use in forming filter cartridgesaccording to the present disclosure.

FIG. 20 is a schematic depiction of various flute definitions.

FIG. 21 is a schematic depiction of a preferred process for use incoiling corrugated media-facing sheet combination, to provide preferredfilter cartridges according to the present disclosure.

DETAILED DESCRIPTION I. Media Configurations Using Fluted Media,Generally

Fluted filter media can be used to provide fluid filter constructions ina variety of manners. One well known manner is as a z-filterconstruction. The term “z-filter construction” as used herein, is meantto refer to a filter construction in which individual ones ofcorrugated, folded or otherwise formed filter flutes are used to definesets of parallel longitudinal inlet and outlet filter flutes for fluidflow through the media; the fluid flowing along the length of theflutes. Some examples of z-filter media are provided in U.S. Pat. Nos.5,820,646; 5,772,883; 5,902,364; 5,792,247; 5,895,574; 6,210,469;6,190,432; 6,350,296; 6,179,890; 6,235,195; Des. 399,944; Des. 428,128;Des. 396,098; Des. 398,046; and, Des. 437,401.

In general, as will be apparent from the following, z-filter media has aset of inlet flutes and a set of outlet flutes. According to the presentdisclosure, preferably at least one of these sets is sealed closed byurethane sealant. Preferred configurations have both sets sealed closedby urethane sealant.

One particular type of z-filter media, utilizes two specific mediacomponents joined together, to form the media construction. The twocomponents are: a fluted (typically corrugated) sheet; and, anon-fluted, non-corrugated (flat) facing sheet. The fluted (typicallycorrugated) media and the non-fluted, non-corrugated (or facing) sheettogether, are used to define parallel inlet and outlet flutes. In someinstances, the fluted sheet and non-fluted sheet are secured togetherand are then coiled to form a z-filter media construction. Sucharrangements are described, for example, in U.S. Pat. Nos. 6,235,195 and6,179,890. In certain other arrangements, some non-coiled sections ofcorrugated media secured to flat media, are stacked on one another, tocreate a filter construction. An example of this is described in FIG. 11of U.S. Pat. No. 5,820,646. Herein the facing sheet may be characterizedas flat, if it is non-corrugated and non-fluted, even if it is coiled inthe filter media construction.

The term “corrugated” used herein to refer to structure in media, ismeant to refer to a flute structure resulting from passing the mediabetween two corrugation rollers, i.e., into a nip or bite between tworollers, each of which has surface features appropriate to cause acorrugation affect in the resulting media. The term “corrugation” is notmeant to refer to flutes that are scored and folded or otherwise formedby techniques not involving passage of media into a bite betweencorrugation rollers. However, the term “corrugated” is meant to applyeven if the media is further modified or deformed after corrugation, forexample by the folding techniques described in PCT/US03/02799,incorporated herein by reference.

Corrugated media is a specific form of fluted media. Fluted media ismedia which has individual flutes (for example formed by corrugating orfolding) extending thereacross.

Serviceable filter element or cartridge configurations utilizingz-filter media are sometimes referred to as “straight through flowconfigurations” or by variants thereof. In general, in this context whatis meant is that the serviceable filtered elements generally have aninlet flow face and an opposite exit flow face, with flow entering andexiting the filter cartridge in generally the same straight throughdirection. The term “serviceable” in this context is meant to refer to amedia containing filter cartridge that is periodically removed andreplaced from a corresponding fluid cleaner. In many instances, each ofthe inlet flow face and outlet flow face will be generally flat, withthe two parallel to one another. However, variations from this arepossible.

The straight through flow configuration is in contrast to serviceablefilter cartridges such as cylindrical pleated filter cartridges of thetype shown in U.S. Pat. No. 6,039,778, incorporated herein by reference,in which the flow generally makes a turn as its passes through theserviceable cartridge. That is, in a U.S. Pat. No. 6,039,778 filter, theflow enters the cylindrical filter cartridge through a side, and thenturns to exit through an end face (in forward-flow systems). Inreverse-flow systems, the flow enters the serviceable cylindricalcartridge through an end face and then turns to exit through a side ofthe filter cartridge. An example of a reverse-flow system is shown inU.S. Pat. No. 5,613,992, incorporated by reference herein.

An example of a typical z-filter media construction is shown in FIGS.1-4. FIG. 1 is a schematic perspective view. FIG. 2 is an enlarged endview of an inlet end portion of a straight through flow filter elementusing a media construction made with the media shown in FIG. 1. FIG. 3is an enlarged end view of and analogous to FIG. 2, but of an opposite,outlet, end. FIG. 4 is an enlarged, schematic, view of a combination ofcorrugated sheet and non-corrugated sheets.

The term “z-filter media construction” and variants thereof as usedherein, is meant to refer to any or all of: a web of corrugated orotherwise fluted media secured to non-corrugated, non-fluted, (facing)media with appropriate sealing to allow for definition of inlet andoutlet flutes; or, such a media coiled or otherwise constructed orformed into a three dimensional network of inlet and outlet flutes;and/or, a filter construction including such media.

Referring to FIG. 1, the z-filter media construction 1 depictedcomprises a fluted sheet, in this instance corrugated sheet 3, and anon-corrugated facing sheet 4 secured to one another. The fluted orcorrugated sheet 3 is secured to the non-corrugated sheet 4 such thatindividual flutes or corrugations 7 (comprising ridges 7 a and troughs 7b when viewed toward side 3 a of sheet 3) extend across thenon-corrugated sheet 4 between opposite ends or edges 8 and 9. For thefinal product, it is a matter of choice whether end (or edge) 8 or end(or edge) 9 is the upstream end or edge. For purposes of the followingdiscussion, it will be assumed that edge 8 is chosen to be the upstreamedge and edge 9 is chosen to be the downstream edge, in the resultingfilter media construction. Thus, arrows 10 indicate the direction offluid flow, during filtering.

Referring to FIG. 1, the corrugated sheet 3 has first and secondopposite sides or surfaces 3 a, 3 b. The second side 3 b is the sidedirected toward the non-corrugated sheet 4, during initial assembly ofthe corrugated sheet 3/flat sheet 4 combination as discussed below;i.e., when the corrugated sheet 3 is first brought into contact with thenon-corrugated sheet 4. (The second side 3 b will sometimes be referredherein as the front side, and the opposite side 3 a as the back side.)

At the upstream edge 8, flutes 11 defined by troughs 7 b of thecorrugations 7 above the corrugated sheet 3, i.e., at side 3 a of sheet3 are open to fluid flow therein in the direction of arrows 12, alongthe upstream edge 8, but are closed to fluid flow therefrom along thedownstream edge 9, by barrier 14, in this instance sealant 14 a. On theother hand, flutes 15, defined by corrugations 7 a on the opposite side3 b of the corrugated sheet 3 from flutes 11, are closed to entrance offluid therein along the upstream edge 8, by barrier 16, in this instancesealant 16 a, but are open to fluid flow outwardly therefrom, along edge9, by the absence of any sealant at this location.

In various prior art z-filter arrangements, a hot melt sealant was used.According to the present disclosure, and the disclosure of U.S.provisional 60/455,643, a preferred sealant material is utilized for oneor more of the sealants 14 a, 16 a. In particular, urethane sealantmaterial, for example a foamed urethane as described herein below inSection III is used.

Of course in the arrangement of FIG. 1, the media is shown not securedin an overall three-dimensional filter element cartridge structure, thatwould complete creation of the isolated parallel flutes 11, 15. This isshown in fragmentary, schematic, in FIG. 2. Referring to FIG. 2, themedia construction 1 is now shown configured in an overallthree-dimensional media pack 20. In general media pack 20, for theembodiment shown, would comprise the media construction 1 of FIG. 1,coiled about itself to create a cylindrical fluted construction 21. Acomplete drawing would typically show a circular or obround filter body.In FIG. 2, only a portion of such a coiled construction 21 is depicted,in particular a portion when viewed toward an upstream surface 22.Herein the term “upstream” when used in this or similar contexts torefer to a surface or edge, is meant to refer to the surface or edgetoward which fluid is directed, for a filtering process. That is, theupstream surface or edge is the surface or edge at which the fluid to befiltered enters the z-filter construction 21. Analogously, the term“downstream” when used to refer to an edge or surface, is meant to referto the edge or surface of a construction 21 from which filtered fluidexits the filtered media construction 21, during use.

It is noted that in FIGS. 2 and 3, the flutes 11, 15 are depictedschematically, as if they have triangular, cross-sections, forsimplicity. The actual curved shape of FIG. 1 would be present in theactual filter, assuming corrugations similar to FIG. 1 were used.

Referring to FIG. 2, at upstream edge 8 or along upstream surface 22,the fluid flow openings in inlet flutes 11 are generally indicated bythe absence of barrier or sealant. Thus inlet flutes 11 are open to thepassage of fluid flow therein. The closed upstream ends of exit flutes15 are also shown, by the presence of a barrier, in this instancesealant. Thus, fluid flow directed against upstream surface 22 can onlypass into the media construction 20, for filtering, by entering theinlet flutes 11. It is noted that in some instances, at the upstreamedge 8, the outlet flutes may not be sealed immediately at the edge 8,but rather may be sealed by a sealant spaced inwardly from the edge 8, aportion of the way down the length of the corresponding flute. Anexample of this is shown, for example, in U.S. Pat. No. 5,820,646, atFIG. 16 thereof. In general, the inlet end of an exit flute will beconsidered sealed at or along an edge or end, as long as the sealant orother structure closing the flute is located (relative to edge 8) eitherat the edge or no more than 25% (preferably no more than 10%) of thedistance between the upstream edge 8 and the opposite downstream edge 9.Usually the sealing is at the edge 8. The description “no more than 25%(or 10%) of the distance between the upstream edge and the oppositedownstream edge 9” in this context is meant to include sealingimmediately at edge 8.

Referring to FIG. 3, the exit edge 9 of the media, forming exit end or23 of the filter construction 21. The exit flutes 15 are shown open, andthe inlet flutes 11 are shown closed by barrier or sealant. The inletflutes 11 will be considered sealed at or along the downstream ends, ormedia edge, as long as the sealant material or other structure closingthe flute, is at the exit edge 9, or within a distance from the edge 9corresponding to no more than 25% of the distance between the oppositeedges 8 and 9. For typical, preferred, embodiments the sealed end ofeach flute 8, 9 would be sealed by sealant positioned at a locationwithin a distance from the closest edge of no more than 10% of the flutelength from edge 8 to edge 9. The sealing can be immediate at the edge9. The description “no more than 25% (or 10%) of the flute length fromedge 8 to edge 9” in this context, is meant to include sealingimmediately at edge 9.

In general, the corrugated sheet 3, FIG. 1 is of a type generallycharacterized herein as having a regular, curved, wave pattern of flutesor corrugations. The term “wave pattern” in this context, is meant torefer to a flute or corrugated pattern of alternating troughs 7 b andridges 7 a. The term “regular” in this context is meant to refer to thefact that the pairs of troughs and ridges (7 b, 7 a) alternate withgenerally the same repeating corrugation (or flute) shape and size.(Also, typically each trough 7 b is substantially an inverse of eachridge 7 a.) The term “regular” is thus meant to indicate that thecorrugation (or flute) pattern comprises troughs and ridges with eachpair (comprising an adjacent trough and ridge) repeating, withoutsubstantial modification in size and shape of the corrugations along atleast 70% of the length of the flutes. The term “substantial” in thiscontext, refers to a modification resulting from a change in the processor form used to create the corrugated or fluted sheet, as opposed tominor variations from the fact that the media sheet 3 is flexible. Withrespect to the characterization of a repeating pattern, it is not meantthat in any given filter construction, an equal number of ridges andtroughs is necessarily present. The media could be terminated, forexample, between a pair comprising a ridge and a trough, or partiallyalong a pair comprising a ridge and a trough. (For example, in FIG. 1the media 1 depicted in fragmentary has eight complete ridges 7 a andseven complete troughs 7 b.) Also, the ends of the troughs and ridgesmay vary from one another. Such variations in ends are disregarded inthe definitions.

In the context of the characterization of a “curved” wave pattern ofcorrugations, the term “curved” is meant to refer to a corrugationpattern that is not the result of a folded or creased shape provided tothe media, but rather the apex 7 a of each ridge and the bottom 7 a ofeach trough is formed along a radiused curve. A typical radius for suchz-filter media would be at least 0.25 mm and typically be not more than3 mm.

An additional characteristic of the particular regular, curved, wavepattern depicted in FIG. 4, for the corrugated sheet 3, is that atapproximately a midpoint 30 between each trough and each adjacent ridge,along most of the length of the flutes, is located a transition regionwhere the curvature inverts. For example, viewing back side face 3 a,FIG. 1, trough 7 b is a concave region, and ridge 7 a is a convexregion. Of course when viewed toward front side face 3 b, trough 7 b ofside 3 a forms a ridge; and, ridge 7 a of face 3 a, forms a trough. Acharacteristic of the particular regular, curved, wave patterncorrugated sheet shown in FIGS. 1-4, is that the individual corrugationsare generally straight. By “straight” in this context, it is meant thatthrough at least 70%, typically at least 80% of the length between edges8 and 9, the troughs do not change substantially in cross-section. Theterm “straight” in reference to corrugation pattern shown in FIGS. 1-4,in part distinguishes the pattern from the tapered flutes of corrugatedmedia described in FIG. 1 of WO 97/40918. The tapered flutes of FIG. 1of WO 97/40918 would be a curved wave pattern, but not a “regular”pattern, or a pattern of straight flutes, as the terms are used herein.

For the particular arrangement shown herein in FIG. 1, the parallelcorrugations are generally straight completely across the media, fromedge 8 to edge 9. Straight flutes or corrugations can be deformed orfolded at selected locations, especially at ends. Modifications at fluteends are generally disregarded in the above definitions of “regular,”“curved” and “wave pattern.”

Attention is again directed to FIG. 3 in which media pack 20 is depictedfrom a viewpoint directed toward downstream end 23 defined by edge 9 ofthe z-filter media construction 1. At this end or surface 23, the exitflutes 15 are depicted open and unsealed, and the entrance flutes 11,are shown closed by a barrier, in this case, by sealant, preferablyurethane. Thus, the only way fluid can exit from downstream end 23 is byflow outwardly from an open exit flute 15.

As a result of the above described construction, fluid which enters theinlet face 22 can only exit from the opposite exit face 23, if the fluidhas passed through the filter media 3, 4. This, in general, is acharacteristic of a z-filter media construction in use namely: (a)individual generally parallel flutes are defined by a media, for examplecorrugated media; and, (b) a closure pattern is provided closingindividual ones of a set of exit flutes at the upstream ends and closingindividual ones of a set of inlet flutes at the downstream ends, forcingfluid flow (with filtering) through one of the media sheets in order forthe fluid to exit from the media pack.

In typical applications involving z-filter media, the media is eithersurrounded by an impermeable shell (as in U.S. Pat. No. 5,820,646), orhas one or more housing seals used at appropriate locations, or both, toprevent fluid flow from going around the media, from a fluid inlet to afluid outlet. The term “housing seal” in this context is meant to referto a seal between the filter cartridge (including the media) and ahousing in which it is installed, for use.

Attention is again directed to FIG. 4, which is an enlarged,fragmentary, schematic, end view of the z-filter media construction 1,showing the corrugated sheet 3 and the non-corrugated sheet 4, but notbarrier or sealant. Again, the configuration of the corrugated sheet, inFIG. 4, will sometimes be referred to herein as a regular, curved, wavepattern of straight flutes.

Z-filter constructions which do not utilize straight, regular curvedwave pattern corrugation shapes are known. For example in Yamada et al.U.S. Pat. No. 5,562,825 corrugation patterns which utilize somewhatsemicircular (in cross section) inlet flutes adjacent narrow V-shaped(with curved sides) exit flutes are shown (see FIGS. 1 and 3, of U.S.Pat. No. 5,562,825). In Matsumoto, et al. U.S. Pat. No. 5,049,326circular (in cross-section) or tubular flutes defined by one sheethaving half tubes attached to another sheet having half tubes, with flatregions between the resulting parallel, straight, flutes are shown, seeFIG. 2 of Matsumoto '326. In Ishii, et al. U.S. Pat. No. 4,925,561(FIG. 1) flutes folded to have a rectangular cross section are shown, inwhich the flutes taper along their lengths. Finally, in WO 97/40918(FIG. 1), flutes or parallel corrugations which have a curved, wavepatterns (from adjacent curved convex and concave troughs) but whichtaper along their lengths (and thus are not straight) are shown. Ingeneral, the filter media is a relatively flexible material, typically anon-woven fibrous material (of cellulose fibers, synthetic fibers orboth) typically including a resin therein, sometimes treated withadditional materials. Thus, it can be conformed or configured into thevarious folded or corrugated patterns, without unacceptable mediadamage. Also, it can be readily coiled or otherwise configured for use,again without unacceptable media damage. Of course, it must be of anature such that it will maintain a corrugated or folded configuration,during use.

In the corrugation process, an inelastic deformation is caused to themedia. This prevents the media from returning to its original shape.However, once the tension is released the flute or corrugations willtend to spring back, recovering only a portion of the stretch andbending that has occurred. The facing (noncorrugated) sheet is oftentacked to the fluted sheet, to inhibit this spring back.

Also, in general, the media contains a resin. During the corrugationprocess, the media can be heated to above the glass transition point ofthe resin. When the resin then cools, it will help to maintain thefluted shapes.

Both of these techniques are generally known in practice, with respectto the formation of corrugated media.

An issue with respect to z-filter constructions relates to closing ofthe individual flute ends. Typically a sealant or adhesive is provided,to accomplish the closure. As is apparent from the discussion above, intypical z-filter media, especially that which uses straight flutes asopposed to tapered flutes, large sealant surface areas (and volume) atboth the upstream end and the downstream end are needed. High qualityseals at these locations are critical to proper operation of the mediastructure that results. The high sealant volume and area, creates issueswith respect to this.

Attention is now directed to FIG. 5, in which a z-filter mediaconstruction 40 utilizing a regular, curved, wave pattern corrugatedsheet 43, and a non-corrugated flat sheet 44, is depicted. The distanceD1, between points 50 and 51, defines the extension of flat media 44 inregion 52 underneath a given corrugated flute 53. The length D2 of thearcuate media for the corrugated flute 53, over the same distance D1 isof course larger than D1, due to the shape of the corrugated flute 53.For a typical regular shaped media used in fluted filter applications,the linear length D2 of the media 53 between points 50 and 51 willgenerally be at least 1.2 times D1. Typically, D2 would be within arange of 1.2-2.0, inclusive. One particularly convenient arrangement forair filters has a configuration in which D2 is about 1.25-1.35×D1. Suchmedia has, for example, been used commercially in Donaldson Powercore™Z-filter arrangements. Herein the ratio D2/D1 will sometimes becharacterized as the flute/flat ratio or media draw for the corrugatedmedia.

In the corrugated cardboard industry, various standard flutes have beendefined. For example the standard E flute, standard X flute, standard Bflute, standard C flute and standard A flute. FIG. 20, attached, incombination with Table A below provides definitions of these flutes.

Donaldson Company, Inc., (DCI) the assignee of the present disclosure,has used variations of the standard A and standard B flutes, in avariety of filter arrangements. These flutes are also defined in FIG. 20and Table A.

TABLE A (Flute definitions for FIG. 20) DCI A: Flute Flute/flat =1.52:1; The Radii (R) are as follows: R1000 = .0675 inch (1.715 mm);R1001 = .0581 inch (1.476 mm); R1002 = .0575 inch (1.461 mm); R1003 =.0681 inch (1.730 mm); DCI B Flute: Flute/flat = 1.32:1; The Radii (R)are as follows: R1004 = .0600 inch (1.524 mm); R1005 = .0520 inch (1.321mm); R1006 = .0500 inch (1.270 mm); R1007 = .0620 inch (1.575 mm); Std.E Flute: Flute/flat = 1.24:1; The Radii (R) are as follows: R1008 =.0200 inch (.508 mm); R1009 = .0300 inch (.762 mm); R1010 = .0100 inch(.254 mm); R1011 = .0400 inch (1.016 mm); Std. X Flute: Flute/flat =1.29:1; The Radii (R) are as follows: R1012 = .0250 inch (.635 mm);R1013 = .0150 inch (.381 mm); Std. B Flute: Flute/flat = 1.29:1; TheRadii (R) are as follows: R1014 = .0410 inch (1.041 mm); R1015 = .0310inch (.7874 mm); R1016 = .0310 inch (.7874 mm); Std. C Flute: Flute/flat= 1.46:1; The Radii (R) are as follows: R1017 = .0720 inch (1.829 mm);R1018 = .0620 inch (1.575 mm); Std. A Flute: Flute/flat = 1.53:1; TheRadii (R) are as follows: R1019 = .0720 inch (1.829 mm); R1020 = .0620inch (1.575 mm).

Of course other, standard, flutes definitions from the corrugated boxindustry are known.

In general, standard flute configurations from the corrugated boxindustry can be used to define corrugation shapes or approximatecorrugation shapes for corrugated media. Comparisons above between theDCI A flute and DCI B flute, and the corrugation industry standard A andstandard B flutes, indicate some convenient variations.

FIGS. 6 and 7 illustrate example filter elements utilizing z-media 74having flutes 120. In FIG. 6, the z-media 74 with the flutes 120 iswound into filter element 202. The filter element 202 includes oppositeflow faces 203, 204 that, in this instance, are parallel. In alternateconfigurations, one of the flow faces 203 or 204 may not be flat or liein a single plane, e.g., it may be conical. An example of a conicallyshaped filter element with z-media is shown in U.S. Des. 399,944; U.S.Des. 428,128; and U.S. Des. 396,098 and z-media with folded flutes canbe configured analogously. The flow face 203 is shown schematically,with only portions showing end flutes 205, but it should be understoodthat the entire filter face 203 will typically have end flutes 205. Inuse, fluid to be filtered enters the upstream flow face (in thisinstance face 204) and exits downstream flow face, in this instance,face 203). The fluid generally flows in the same direction entering theupstream flow face 204 as it exits the downstream flow face 203. Again,this configuration generally referred to herein as a “straight throughflow” filter.

As can be seen in FIG. 6, the particular filter element 202 is round, inthat it has a circular cross-section. When using the filter element 202in an air cleaner system, the filter element 202 may be modified byplacing an appropriate gasket or other type of sealing members thereon.One example housing seal or sealing gasket 208 is shown secured to anouter cylindrical surface 209 of the element 202. The sealing gasket 208shown includes foamed polyurethane and forms a seal with a housing bycompression of the gasket 208 against the housing. Examples of usablesealing gaskets include the ones described in U.S. Pat. No. 6,190,432and U.S. patent application Ser. No. 09/875,844, filed Jun. 6, 2001, andcommonly assigned hereto.

FIG. 7 illustrates another example of a filter element 216 utilizingz-media 74 and wound into the filter element 216. As with the filterelement 202 shown in FIG. 26, the filter element 216 has opposite flowfaces 217, 218 to accommodate straight through gas flow. As with theFIG. 26 embodiment, this embodiment also shows the flow face 217schematically, with only portions showing end flutes, but it should beunderstood that the entire filter face 217 typically will show the endflutes. In this embodiment, the filter element 216 is obround.Specifically, this particular filter element 216 has a cross-section inthe shape of two generally parallel sides 219, 220 joined at their endsby curved portions 221, 222. This shape is sometimes referred to hereinas a “racetrack shape.” The filter element 216 may include appropriatehousing seals or gaskets, and in the example shown, includes the type ofsealing member 224 described in U.S. Pat. No. 6,190,432. This sealingmember 224 includes polyurethane mounted on (or molded) on a frame,secured to the element 216. In each of the elements 202, 216, a centralcore 226, 227 is shown as having the z-media 74 wound therearound.

The filter media described herein can be made into elements, of whichexamples are shown in FIGS. 6 and 7. The filter elements are useable influid (liquid or air) cleaners. One such system, for air filtration, isdepicted schematically in FIG. 8 generally at 230. In FIG. 8, equipment232, such as a vehicle, having an engine 233, with some defined ratedcombustion air flow demand, for example at least 300 cfm, for example500-1200 cfm, is shown schematically. Equipment 232 can include a bus,an over-the-highway truck, an off-road vehicle, a tractor, or marineequipment such as a powerboat. The engine 233 powers the equipment 232,through the use of an air and fuel mixture. In FIG. 8, the air flow isshown drawn into the engine 232 at an intake region 235. An optionalturbo 236 is shown in phantom, as optionally boosting the air intakeinto the engine 233. An air cleaner 240 having a filter construction 242is upstream of the engine 232 and the turbo 236. In general, inoperation, air is drawn in at arrow 244 into the air cleaner 240 andthrough the primary element 242. There, particles and contaminants areremoved from the air. The cleaned air flows downstream at arrow 246 intothe intake 235. From there, the air flows into the engine 233 to powerthe equipment 232.

Other examples of useable systems include intake air filters gas turbinesystems. Of course the media can also be used in liquid (for example oil(lubrication), fuel or hydraulic) filters.

Attention is now directed to FIG. 19, in which a process for manufactureof media usable to form arrangements is characterized herein, as shown.Referring to FIG. 19, at 300, roll stock of media 301 usable to formcorrugated media shown. A continuous web of media 301 is shown directedinto a bite 303 between corrugation roller 304 and 305. Exiting from thecorrugation bite 303 is shown a resulting continuous corrugated web 307.

Still referring to FIG. 19, a second roller 320 of media 321 is shown.The media 321 is a continuous web directed into location 322, whereat itis supplied as a facing sheet to a side of corrugated sheet 307. Media321 is preferably a non-fluted, non-corrugated media.

In general, sealant is applied between the corrugated media 307 and thefacing sheet 321, to form seals at one edge of a resulting filter mediacombination. Two (convenient) optional locations for application of thesealant shown. At 325 one preferred location is provided, in which thesealant is applied to sheet 301 before corrugation, to a side which willface sheet 321 when they are joined. When applied at this location,preferably in bite 303 a gap is provided, to accommodate the sealantbead. An alternate optional location is shown at 325 a, in which thesealant is applied to a side of web 321 which will be facing corrugatedsheet 307, when they are joined.

In either case (325, 325 a) for the process shown, the sealant orsealant strip is applied mid-web, although alternatives, discussedbelow, are possible. After the corrugated web 307 and facing sheet 321are joined to form a corrugated/facing sheet combination 330, thecombination is directed to a slitter 340, which will slit the combinedweb into two strips 341, 342. The slitter 340 uses a knife edgepreferably organized to split the combination directly through the sealbead, so that each resulting strip 341, 342 will be completely sealedalong one edge between the corrugated sheet and the facing sheet. Such aprocess will sometimes be characterized as a mid-web sealant process,and it makes two strips of media at once.

In an alternate process, the sealant or sealant strip would be appliedalong an edge, between two media webs 301, 321, to form one strip ofmedia.

The preferred sealant is a urethane, as described herein, if thecorrugation is not folded. In prior art processes, a hot melt wastypically used.

In some applications, a mid-web fold process in accord with PCTPCT/US03/02799 and U.S. provisional 60/395,009 can be used, beforeslitting. In such instances, a hot melt adhesive may be preferred in thefolded flute end.

The next step depends upon the type of structure to be made. In someinstances the resulting corrugated sheet/facing sheet strip is cut intosections, which are stacked on one another with sealant beadappropriately therebetween, to provide sealing at the opposite end ofthe media. In an alternate process, a selected corrugated sheet/facingsheet strip is coiled to form a coiled media construction. Such coilingis generally done with the facing sheet to the outside of the coil, andthe corrugated sheet to the inside. Sealant is shown applied to thecorrugated sheet at an opposite edge from the edge at which sealant isbetween the corrugated sheet and the facing sheet. This sealant strip,during the coiling, will become positioned between the corrugated sheetand the back side of the facing sheet, as the coiling around occurs. By“backside” of the facing sheet in this context, is meant a side of thefacing sheet that is directed away from the corrugated sheet beforecoiling. (The opposite side will be called the front side.) Similarly,the “backside” of the corrugated sheet will be referred to as the sidedirected away from the facing sheet, before coiling. (The opposite sidewill be called the front side.)

The back side sealant applied before or during coiling, is preferablyurethane in accord with the present disclosure. In the prior art, hotmelt was typically used.

II. Processing Advantages and Options With Urethane Sealant

The use of a slower curing sealant such as a urethane sealant in placeof hot melt, provides for the possibility of number of advantages.Unlike hot melt, the preferred sealant is provided in a form that willfoam as it cures. As the sealant material foams during cure, it expandsin size. This reduces the likelihood of leak formation. Further, asealant material that is slower to cure, than the time in which hot melthardens from cooling, is advantageous. For example, some shapemanipulation of the media, to advantage, can occur after sealant isapplied and while the sealant is still in a curing stage, without leakformation, if a sealant like urethane sealant is used instead of hotmelt. The flexibility afforded by this, can be used to generate certaintypes of constructions to advantage, as described. Also, urethanesealant, specifically, can be advantageous relative to hot melt, becauseurethane maintains its integrity in higher temperature conditions, thantypical hot melt. For example, hot melt can soften enough to distortafter extended exposure (about 2 hrs) to temperatures of about 180° F.

Examples of a preferred filter cartridge construction manufacturableutilizing a preferred process according to the present disclosure, areprovided in FIGS. 9 and 10. Referring to FIG. 9, the filter cartridge350 depicted generally comprises a coiled z-filter media construction351 having framework 352 mounted thereon. The framework 352 includes ahousing seal or seal ring 353 thereon. A typical housing seal 353 willbe formed from a urethane or other material. The framework 352 is sizedto engage portions of a housing, not shown, in a sealing manner to sealfilter media construction 351 in place. In typical operation, air flowwould enter upstream face 355 and exit downstream face 356. Typically,framework 352 (except for seal 353) is a rigid molded plastic, but metalconstructions can be used. Again, the term “housing seal” and variantsthereof, is meant to refer to a seal mounted on the filter cartridgeconstruction, for providing a seal between the cartridge constructionand a housing, in use.

Cross pieces 357 of framework 352 generally provide strength toframework construction 352. In some prior art applications with hotmelt, such cross pieces also were used as a face lattice to inhibittelescoping of the media construction 351 in the direction of arrow 360;i.e., in the direction of air flow. However, in general, when a urethanesealant material as described herein is used, telescoping effects areminimal. This is an advantage relative to the use of hot melt, which, asit softens under conditions of heat, can permit some distortion ortelescoping of the associated media construction (in the absence offramework to inhibit the telescoping). Thus, in some arrangementsimproved media as characterized herein can be used without an outerimpermeable sheath and also without added framework or with addedframework that does not have cross-pieces that prevent telescoping.

Attention is now directed to FIG. 10, which is a top plan view of FIG.9. Referring to FIG. 10, it is noted that the media construction 351does not include an added center piece around which the media is wound.This is because the filter construction 350 was constructed in accordwith a preferred process enabled by the utilization of a urethanesealant material, as described. This preferred process will be describedby reference to FIG. 11. (The term “added center piece” and variantsthereof, in this context, is meant to refer to a board, core, or otherpiece separate from the media strip.)

Referring to FIG. 11, at 400, a strip of fluted (specificallycorrugated) media 401 secured to a facing sheet 402 is shown. Along oneside edge, the two would be sealed together by a front side, preferablyurethane, seal bead. (The combination could have been made utilizing aprocess analogous to that described above for FIG. 19.) In a first stepof using the fluted sheet-facing sheet combination, a back side sealantbead is applied either: (1) to surface 405 of the fluted (in thisinstance corrugated) sheet 401, on a back side or opposite side fromfacing sheet 402, and along an edge opposite to that along which thefront side sealant bead is positioned between sheets 401 and 402 to sealthem to one another; or, (2) to a back side 406 of the fluted (in thisinstance corrugated) sheet 401, again along an edge opposite to thefront side seal. The combination 400 with the backside sealant bead iscoiled, in the direction of arrow 406, with the flutes (or corrugations)directed to the inside of the coil and with the facing sheet 402directed to the outside of the coil to form to form a first coil orconfiguration. At 410, such a coil is shown, schematically. Theparticular coil 410 shown is generally circular, around a central openspace 411, however alternate shapes are possible. The coiling could havebeen around a mandrel which is removed to provide for the open space411. The circumference of the open space 411 will be selected, asdiscussed below. A lead or front end of the media strip 400 directedinto the coiling, is shown at 413. An opposite rear or tail end is shownat 414. A typical coil, for many air filter applications, would have anoutside perimeter of at least 30 cm., often at least 60 cm., for example70-160 cm. Typically it will be made by winding the media at least 6times around, typically at least 10 times.

The net result of the coiling, whether around a hub or mandrel (which islater removed) or around an open space, is to provide a constructionsuch as that shown at 410, which is coiled with a central opening 411.(That is, the open space is distorted in shape.) Such a construction canthen be distorted from its original shape, to a second shape. The secondconfiguration or shape would typically, for many air filterapplications, have an outside perimeter of at least 30 cm., often atleast 60 cm. An example of a second shape is an obround shape as shownat 440. In a later step, a framework such as framework 352, FIG. 9, canbe added, if desired.

In general, the length of a center strip 441 in construction 440 betweenends 441 a, 441 b will be about one-half of the circumference of openingor open space 411. Thus, the circumference of opening 411 should beselected to provide the preferred size of strip 441, for a selectedapplication.

The particular, preferred, construction 440 depicted is sometimesreferred to herein as having a racetrack shape, with the typicalfeatures being: two opposite, generally parallel, straight sides 443,444; and, opposite, rounded, ends indicated at 445, 446, generally eachbeing approximately semi-circular. The opposite sides 443, 444, do notneed to be precisely parallel or perfectly straight.

Distortion of a first, coil or, wound arrangement, such as structure410, to a second, arrangement, for example to an obround arrangementsuch as 440, is facilitated when urethane is used for the backsidesealant bead in the winding operation. This is in part because urethaneis relatively flexible, by comparison to hot melt. In addition, becausethe urethane is relatively slow to fully cure, the distortion can bemade to occur before the urethane material of at least the back sidebead is fully set. It is also facilitated by utilizing a sealantmaterial that foams, since it expands as it cures, and will tend to fillspaces and inhibit leaks.

When a strip of corrugated media secured to a facing sheet is coiled,two ends are defined. The first end, characterized herein as the leadend, forms an inner most end inside of the coil 410. In FIG. 11, thelead edge is indicated generally at 413. The second end, generallyreferred to herein as the “tail end,” is the end of the strip leftagainst the outside of the media coil 410. In FIG. 11, the tail end isindicated at 414.

A preferred process approach for coiling media is described in Section Vbelow, in connection with the description of FIG. 21. Such a process canbe applied, as a specific form of the process described in FIG. 11, toprovide preferred media constructions according to the presentdescription. It can also be applied with alternate z-filterconfigurations, and even z-filter configurations utilizing alternateseal material, if desired.

Attention is now directed to FIGS. 12-18. In FIG. 12, a top plan view ofa filter element 500 generally in accord with the arrangement of FIGS. 9and 10, is depicted. Referring to FIG. 12, filter media construction 501is viewable, having framework 502 mounted thereon. The mediaconstruction 501 is generally in a racetrack shape, as described above.The media construction 501 includes no added center piece around whichthe media is coiled.

The media construction 501 generally comprises a coiled strip 504 ofcorrugated media secured to facing sheet, made in accord with theprocess of FIG. 11.

In FIG. 13, an enlarged fragmentary view of the filter element 500 isdepicted. In FIG. 13, a media center strip 510, around which a remainderof the strip 502 is coiled, is readily viewable. The media center 510 iseasily viewed to be without a center board or piece around which themedia is coiled. That is, the media 502 is simply coiled around itself.A first, substantially straight, lead strip 511 is readily viewable,extending from lead end 511 a along strip 512 to first bend 513. Themedia 502 then extends along second, substantially straight, strip 514until a second turn 515 is encountered. This results in one completeturn or coil, with further turns, or progressively outside coils,following. Sections 512 and 514 generally result from an innermost turn518 of coil 410, FIG. 11, after compression or distortion to theracetrack shape.

Referring to FIG. 13, it is noted that the coiling was conducted withthe corrugated sheet toward the inside and the facing sheet directedoutside. Also, in sections of strips 512 and 514, the flutes (in thepreferred instance shown, the corrugations) are interdigitated. The term“interdigitated” in this context, is meant to refer to the fact that inat least portions of strip 512, selected ones of flutes or corrugationsin the strip 512 are each directed into troughs between selected ones offlutes or corrugations of strip 514; and, along at least portions ofstrip 514, selected ones of flutes or corrugations are directed intotroughs between selected ones of flutes or corrugations of strip 512.

Herein, when two strips are said to be interdigitated over an extensionof at least N flutes or corrugations, it is meant that at least Nsequential flutes or corrugations of one strip are interdigitatedbetween adjacent ones of N+1 sequential flutes or corrugations ofanother strip. For example in FIG. 13, the two strips 512, 514 areinterdigitated over an extension of at least 15 corrugations, so atleast 15 sequential individual corrugations of strip 512 are eachpositioned between adjacent ones of 16 sequential, individual,corrugations of strip 514. Generally, and preferably, for preferredarrangements, an interdigitation for one strip of at least six (6)flutes or corrugations, typically at least fifteen (15) flutes orcorrugations, will be preferred. Often an interdigitation of at least 20flutes or corrugations, as shown in FIG. 13, will be used.

The provision of interdigitated flutes or corrugations, along a centerstrip of a media pack deformed from a circular coil of a single strip,is advantageous for a number of reasons. For example, space savingsresults. Also, a more secure arrangement with respect to media movementresults. In addition, some advantage to fluid flow is obtained. Ofcourse, an added center piece has also been avoided.

A space 520, at an inner end of the coil, can be filled, for exampleadjacent one flow face of the media construction, with sealant toprevent unfiltered flow through the construction. A foamed sealant, suchas a foamed polyurethane, will be preferred.

It is noted that in FIG. 13, the tail end of the media can be seen at525, located adjacent one of the straight sides.

Attention is now directed to FIG. 14, which is an enlarged fragmentaryview of a portion of FIG. 13. Here, center strips 512, 514 havinginterdigitated segments, can be more readily seen. Of course strips 512,514 are sections of a single coiled strip media material comprising acorrugated sheet-facing sheet combination.

Attention is now directed to FIG. 15. In FIG. 15, the tail end 525 isshown sealed (and secured against side 526) completely along its lengthby a sealant 527, in this instance hot melt. In FIG. 16, sealant 527 andtail 525 are similarly viewable.

By the sealant 527 extending completely along the length of tail end525, an undesirable level of leakage from between the corrugated sheetand the facing sheet at the tail end, is inhibited.

With respect to the lead end 511 a, FIG. 14, in general sealing of thecorrugated (or fluted) sheet to the flat sheet, completely along thisend, if desired, could be conducted prior to coiling. It has beenobserved, however, that when the center strip 511, FIG. 14, is formedwith preferred, interdigitation, leakage from between the corrugatedsheet and the flat sheet at this location, can be reduced toinsignificant levels, even in the absence of sealant (between the twosheets) that extends completely across the lead end.

Attention is now directed to FIG. 17. FIG. 17 is an enlarged schematicview depicting the center strip of a media coil, in this instance theview is toward the inlet end or dirty side of the media construction.Referring to FIG. 17, the media coil is generally indicated at 600. Acenter strip, with interdigitated flutes or corrugations, is indicatedat 601. The lead end of the media is generally indicated at 605. Sealantalong that lead end 605, immediately adjacent edge 602, was provided bysealant 610, preferably urethane sealant. Sealant at this location wouldhave resulted from foaming and curing (with volume expansion) of sealantoriginally positioned in regions 611, 612, during a process as describedabove with respect to FIG. 11. During cure, additional sealant can beadded, to fill any open space at this location, if desired. This isfacilitated by using a foamed sealant such as urethane.

FIG. 18 is a perspective view of the media section shown in FIG. 17,with reference numerals indicating similar features.

Referring to FIG. 11, preferably the deformation of coil 410 to yieldshape 440 is conducted so that the tail end 414 of the media from thecoiling is along one of the straight sides 443, 444 and, not at one ofthe curved ends 445,446. This is preferred since it leads to a moresecure closing of the tail end 414.

III. Some General Observations and Principles

In general, the techniques previously described can be used to providefor preferred fluted filter media constructions. In this context, theterm “fluted filter media construction” is meant to refer to a filterconstruction which includes the media, whether the construction is themedia itself or the media provided in the form of an overall serviceablefilter element or cartridge, through addition of a seal for sealing to ahousing and/or framework.

Also according to the present disclosure, for example as described withreference to FIG. 19, processes for manufacturing a filter mediaconstruction including a sheet of fluted (typically corrugated) filtermedia having curved wave pattern of corrugations are provided.Preferably the processes are conducted on a sheet of corrugated mediahaving a curved wave pattern of corrugations secured to a non-flutedfacing sheet.

The process may be conducted to form strips in a mid-web sealingprocess, with follow-up slitting. It also may be conducted to form astrip provided with sealing along a web edge (not made by a mid-websealing process). The process may involve flute folding, in accord withPCT/US03/02799 and/or U.S. provisional 60/395,009.

In a typical such process, the corrugated sheet or web would be formedby passing a non-corrugated sheet into the bite between corrugationrollers. In some processes sealant may be provided on the corrugatedsheet prior to deformation, by providing the sealant on the web when itis passed into the corrugating rollers, to form the corrugated sheet.This can be advantageous for reasons previously discussed.

Also according to the disclosure a method for preparing of fluid filtermedia construction is provided. The method, is generally characterizedwith respect to the description of FIG. 11, includes a first step ofcoiling a media strip comprising a fluted sheet secured to a non-flutedsheet, into a first coiled configuration. The first coiled configurationwould typically be circular, although alternatives are possible. Thecoiling could be around a mandrel which is later removed, or around anopen space. In general the coiled media strip would include a front sidesealant strip between the fluted sheet and facing sheet, along a firstside edge; and, there would also be provided a back side sealant stripbetween the fluted sheet and the facing sheet along a second side edge.

After the step of coiling, and in the absence of added center piece, thefirst coiled configuration would be deformed into a second coiledconfiguration. A typical second coiled configuration would be a racetrack shape or similar shape, having interdigitated corrugations orflutes, along an inside strip.

In a preferred process, the back side sealant strip is polyurethane,more preferably polyurethane which foams during cure to provide a foamedpolyurethane. Preferably the material is selected to provide at leastsix interdigitated flutes, more preferably at least 15 interdigitatedflutes and most preferably at least 20 interdigitated flutes along theinner strip. Preferably the inner strip is at least 6 cm. long, morepreferably at least 12 cm. long.

The front side sealant strip may be polyurethane (preferably foamedpolyurethane). However, if the corrugated sheet-facing sheet is madewith one set of flute ends folded closed between the corrugated andfacing sheets, along the front side seal typically a hot melt would beused.

Preferably the process is conducted with corrugated media, secured tonon-corrugated media, preferably with a flute/flat ratio within therange of 1.2-2.0, more preferably 1.25-1.35.

Preferably the deformation is conducted such that a tail end of themedia strip, of the first coil, is positioned along a straight portionof the second coiled configuration. It is preferably sealed against astraight side section of the second coiled configuration, using asealant, for example hot melt.

In typical applications, the step of coiling to form the first coilconfiguration will be conducted to provide a configuration having anoutside perimeter of at least 30 cm., typically at least 60 cm., forexample 70 to 160 cm.

In a typical process, a follow-up step of adding a framework to helpmaintain the media in the preferred second coiled configuration, as wellas to support a housing seal, can be provided. However, alternateconfigurations, for example in which a seal is directly applied to themedia coil as opposed to using any added framework, are possible. Inthis latter approach, added framework, to provide cross-pieces orlattice across either flow face, can be avoided.

In general, the principles herein relate to a preferred filter mediaconstruction including coiled media strip comprising a fluted sheetsecured to a non-fluted sheet is provided. The preferred construction isone having no added center piece and including a strip having at leastsix interdigitated corrugations. However, alternate preferredconstructions, involving the preferred choice of a urethane, inparticular a foamed urethane, for the sealant to close ends of theflutes are possible. Preferably a race track shape configuration isprovided, with two opposite generally straight parallel sides, and twocurved ends. Preferably a perimeter size of at least 30 cm., preferablyat least 60 cm., and typically 70 to 160 cm., will be chosen.

IV. Urethane Sealant Use

In general, in prior art z-filter systems hot melt adhesives were used,to seal the ends of flutes. According to the present disclosurepreferred processes are conducted, to prepare preferred materials, whichutilize urethane as the sealant.

Typically, two sealant beads are involved in the creation of z-filterelements. The first is the seal bead positioned between the corrugatedmedia and the facing or non-corrugated sheet, as the two sheet mediacomposite is constructed, as described herein. The sealant bead can beapplied either to the facing or flat sheet, or it can be applied to thematerial which will be corrugated to form the corrugating sheet, beforecorrugation occurs, as described herein above. In some applications aurethane sealant (preferably one that foams during cure) can be used atthis location, to advantage. In others, a hot melt can be used,especially if media folding of these flutes is involved.

The second sealant location is sometimes referred to as the winder bead,and is the sealant bead that forms the seal at the opposite side of thecorrugation sheet, from the sealant bead between the corrugated sheetand the facing sheet to which it is secured. This sealant bead issometimes called the winder bead because it is often applied to thecorrugating sheet as the winding process occurs. Herein, it will also becalled the back side sealant bead. Urethane (most preferably one thatfoams during cure) is preferred for this sealant.

The urethane will typically be in the form of two component urethane. Ingeneral, a two component urethane is one which cures upon mixture of twocomponents together, typically with an appropriate catalyst present. Anexample would be a urethane made from a resin mixed with a isocyanatecomposition, as described below. A variety of specific urethaneformulations can be used, the example is to indicate a typical useablematerial. Specific choice will be based on such factors as cost,availability and handling properties.

In general, a two component urethane as characterized herein below, is afoamed urethane that expands as it cures. Indeed, preferably theurethane is chosen so that it will expand in volume at least 40%,typically 50% to 100%. An advantage to this relative to a hot melt, isthat the expanding urethane will push its way into open spaces in mediamaterial at the sealant location, and help form a more secure seal.

Secondly, the urethane is self reactive and takes some period of time tocure. As a result, the media material can still be handled andmanipulated after the urethane has been placed on the media material,without as great a risk of opening leaks or seal failures as with a hotmelt. For example, self foaming urethane can be applied as a sealant ina winding bead, and the media can then still be manipulated from acircular wind into another shape, as the urethane cures.

Urethane is more capable of withstanding higher temperature conditions,than are typical hot melts. Thus it can be advantageous depending on theenvironment of use of the z-filter media involved.

A typical preferred urethane would be a blown urethane that cures to afoam urethane having an “as molded” density of no greater than 28 lbs.per cubic foot, preferably no more than 22 lbs. per cubic foot,typically no greater than 18 lbs. per cubic foot. The particular foamedurethane chosen density will depend upon the specific level of sealintegrity required. It is expected that the “as molded density” willtypically be within the range of 8 lbs. per cubic foot-17 lbs. per cubicfoot.

Herein the term “as molded density” is meant to refer to its normaldefinition of weight divided by volume. A water displacement test orsimilar test can be utilized to determine volume of a sample of themolded urethane foam. It is not necessarily applying the volume test, topursue water absorption into the pores of the porous material and todisplace the air in the pores. Thus, the water volume displacement testused, to determine sample volume, would be an immediate displacement,without waiting for a long period of displaced air within the materialpores. Alternately stated, only the volume presented by the outerperimeter of the sample need be used for the as molded calculation.

Urethane resin systems usable to provide materials having physicalproperties within the as molded density definition provided above, canbe readily obtained from a variety of polyurethane resin formulators,including such suppliers as BASF Corp., Wyandot, Mich. 48192.

One example usable material includes the following polyurethane,processed to an end product having an “as molded” density as described.The polyurethane comprises a material made with I36070R resin and I305OUisocyanate, which are sold exclusively to the assignee Donaldson by BASFCorporation, Wyandotte, Mich. 48192.

The materials would typically be mixed in a mix ratio of 100 partsI36070R resin to 45.5 parts I3050U isocyanate (by weight). The specificgravity of the resin is 1.04 (8.7 lbs/gallon) and for the isocyanate itis 1.20 (10 lbs/gallon). The materials are typically mixed with a highdynamic shear mixer. The component temperatures should be 70-95° F.

The resin material I36070R has the following description:

-   -   (a) Average molecular weight    -   1) Base polyether polyol=500-15,000    -   2) Diols=0-10,000    -   3) Triols=500-15,000    -   (b) Average functionality    -   1) total system=1.5-3.2    -   (c) Hydroxyl number    -   1) total systems=100-300    -   (d) Catalysts    -   1) amine=Air Products 0.1-3.0 PPH    -   (e) Surfactants    -   1) total system=0.1-2.0 PPH    -   (f) Water    -   1) total system=0.2-0.5%    -   (g) Pigments/dyes (optional)    -   1) total system=1-5% carbon black    -   (h) Blowing agent    -   1) water.

The I3050U isocyanate description is as follows:

-   -   (a) NCO content—22.4-23.4 wt %    -   (b) Viscosity, cps at 25° C.=600-800    -   (c) Density=1.21 g/cm³ at 25° C.    -   (d) Initial boiling pt.—190° C. at 5 mm Hg    -   (e) Vapor pressure=0.0002 Hg at 25° C.    -   (f) Appearance—colorless liquid    -   (g) Flash point (Densky-Martins closed cup)=200° C.

The urethane usable as the sealant material to close flutes in thez-filter media can be the same as the sealant material utilized toprovide seal gaskets for engagement between the filter element and anassociated air cleaner.

It is noted that the preferred formulation characterized above indicatesthe optional presence of a pigment or dye in the urethane. The urethanecan be used in its natural, uncolored, state. As an alternative toblack, it can be provided with colored dyes.

For typical use in sealant beads, whether it is the front side beadbetween the corrugated media and the facing sheet when the combinationof the two is first formed, or when used as a winding bead when thecombination is coiled into a media construction, the application amountof the sealant will be typically within the range of about 4-8 grams permeter on the media. However, amounts outside of this range can be usedin some instances, depending on the particular media size and shape, aswell as the particular urethane density.

Typically the urethane would be mixed and then dispensed at about roomtemperature or about 70° up to about 95° F. The media to which theurethane is applied may be heated, depending upon other processingsteps. However, there is no requirement that the media had been heatedabove room temperature, for typical urethane applications.

The sealant will typically be applied in a bead having a width on theorder of about ¼ inch-1 inch, typically ½ inch-¾ inch. When the bead isbeing applied as part of the mid-web approach, to create a seal betweena facing sheet and a corrugating sheet which is then to be slit tocreate two webs, typically a sealant bead having a width on the order ofthe wider end of the range will be preferred. On the other hand, whenapplied merely at an edge of media, either as a winding bead or as asealant bead when the corrugation sheet/facing sheet is generated, awidth on the narrower end of the range be usable.

V. A Preferred Z-Filter Media Coiling Process

Attention is now directed to FIG. 21. FIG. 21 is a schematic depictionof a useful media coiling process. Referring to FIG. 21, strip 800 ofmedia 801 to be coiled, is shown. The media 801 comprises a fluted, inthis instance, corrugated, sheet 802 secured to a non-fluted,non-corrugated, facing sheet 803. The two are preferably securedtogether with a front side sealant bead or strip utilizing a urethane(preferably foamed) sealant, although alternatives are possible. Themedia strip 800, during the process, generally moves in the direction ofarrow 810. The media strip 800 is shown positioned on a media guide 811.The media strip 800 may be in accord with the variations described orreferenced herein. Thus, it could, for example, have flutes with foldedends.

The processing equipment for the coiling generally comprises a mediawinding mandrel or hub 812. The diameter of the winding hub 812 will beselected to provide a desired diameter for central opening 411, FIG. 11.The media winding hub 812 is mounted to rotate, in this instance in thedirection of arrow 815 around a center axis 816. The hub 812 includes amedia catch slot 817 therein. The media catch slot 817 extends adistance, from an outer perimeter 820 to an inner most recess 821,corresponding to a preferred length for inside tail 822 of media 801during a winding process. Typically a length for tail 822 will be atleast 0.75 inch, usually at less 1 inch, for example 1.25-2.5 inches.

In general, the media winding hub 812 is initially positioned such thatmouth or gap 825 at an outer edge 820 of media catch slot 817 ispositioned to receive media strip 800 as it moves in the direction ofarrow 810. A locking pin or similar structure, not shown, can beutilized to maintain the winding hub 812 in this rotational orientationrelative to the media guide 811, during projection of media end 822 intocatch slot 817. In FIG. 21, the winding hub 812 is shown positioned in amedia receiving orientation. That is the hub 812 is positioned with gap825 oriented with lower edge 825 a positioned adjacent end 811 a ofmedia guide 811, so that media 801 moving in the direction of arrow 810will enter slot 817.

During a winding operation, the media strip 801 is pushed into the mediacatch slot 817 a selected distance which can be controlled withautomated equipment monitoring the timing of insertion allowed beforethe winding hub 812 rotated.

In preferred assemblies and practices, a media catch arrangement isprovided to secure the media tail 822 in slot 817, during a windingoperation. The media catch arrangement may comprise a variety ofalternate mechanical constructions. In general all that is needed is aconvenient arrangement to hold tail 822 in place, during the winding orcoiling.

A particular convenient media catch arrangement utilizes a catch or lockpiece which can be pushed out of the way as the media end 822 isinserted, and which catches the media end 822 against reverse pull. Theparticular arrangement depicted, utilizes a floating media lockingroller 850 for this purpose.

The media locking roller 850 is operably positioned within the catchslot 817. In particular, portion 851 of the catch slot 817 includes agroove 852 therein, with a front catch 853, to maintain roller 850 inthe groove 852. The axial length of roller 850 is typically less thanthe axial length of the groove 817. For example, the roller 850 may onlyextend over about one-third of the axial length of the winding hub 812,whereas in general the catch slot 817 would extend the entire length ornearly the entire length, of the roller 812.

The diameter of the media locking roller 850 can be selected to be largeenough so that it doesn't fit into end 855 of catch slot 817. Further,the diameter is selected so that roller 850 will tend to nest,partially, between media corrugations, as shown, inhibiting the easewith which the media strip 810 can be pulled out of the media catch slot817. As a result, the floating media locking roller 850 will help holdtail 822 of the media strip 801 is position, during coiling.

After the media strip 801 is directed sufficiently far into the mediacatch slot 817, and the media locking roller 850 is in place, thewinding hub 812 can be rotated to wind or coil the media 801 aroundouter surface 812 a. Preferably the winding is with the facing sheet 803directed out, and the corrugation sheet 802 directed in. The windingwill continue a sufficient number of times to produce the desired woundcoiled media construction. Typically, the media strip 800 is cut to aparticular length, prior to coiling. Thus, coiling typically continuesuntil the complete strip length is taken out. In alternate processing,the media could be cut after a sufficient or defined amount of coilinghas occurred. A backside sealant strip, or bead, could be applied beforeor during the winding process. Some preferred sealant beads aredescribed below.

After coiling around hub 812, the resulting media coil can be slid fromthe winding hub by axial movement or ejection, for example (in referenceto FIG. 21), toward the viewer. The media guide 811 can be positionedand configured to be moved out of the way, during this step. The portionof the media strip after coiling, which corresponds to the portion 822contained with the catch slot 817, after removal from the winding hub812, will rest back against an inside surface of the coil, to provide acoil generally as shown in FIG. 11 at 410. The locking roller 850, doesnot interfere with axial ejection of the media coil from the hub 812.

The resulting coil 410, FIG. 11, can be distorted to an obround shape440, as described above with respect to FIG. 11. In some instances itmay be desired not to have an interdigitated racetrack shape result. Toavoid interdigitation adjacent the backside sealant bead, all that isgenerally required is to put a temporary center piece such as a flatsheet inside of opening 411, FIG. 11, before distortion or crushing tothe racetrack shape. For example 1/16 inch thick plastic sheet(preferably a polyolefin to which urethane does not stick well) could beused, having a width corresponding to the diameter of region 411. Thesheet would not typically project all the way through the axial lengthof the coiled media, since interference with the backside sealant beadshould be avoided. In general, it would be inserted into an end remotefor the backside sealant bead, to stop, short of the backside sealantbead, for example at a position about one-quarter inch to two inchesfrom the end of the sealant bead depending on how much foaming isexpected. After the urethane of the backside sealant bead issufficiently set, the temporary center piece could be removed, toprovide for a coiled media construction having no added center piece andwhich also is not interdigitated, especially at least at the endcorresponding to the backside sealant bead. In some instances avoidanceof interdigitation, at least at this end, can provide advantage withrespect to dust load in the resulting filter element.

As explained previously, when a foamed urethane is used for the backsidesealant bead, after coiling the foaming action of the sealant willincrease its volume. In general it is preferred to space the backsidesealant bead sufficiently away from the nearest edge of the media, sothat as the material foams, it does not bubble outwardly from the edgeof the media. Typically a spacing of about 0.25 inch-1.0 inch will besufficient, depending upon the amount of sealant in the bead.

In some instances it may be desirable to apply a greater amount ofsealant in selected portions of the backside sealant bead, than inothers. Two locations where it may be desirable to apply more sealant,are adjacent to lead front end 413, FIG. 11, and immediately adjacentthe tail end 414, FIG. 11. With respect to the front end 413, it may bedesirable to have more sealant bead within the first one to threewindings along the inside of the racetrack shape, for example. If theamount of sealant in this location is to be increased, it may bedesirable to position the backside sealant bead, at this location,further away from the nearest edge, than at locations where less sealantis used, to avoid undesirable bubbling of the foaming sealant out,during cure.

Again, it may be desirable to provide a greater amount of sealant in thelast outside wind adjacent the tail end 414, FIG. 11. At this location,it may be desirable to similarly position the backside sealant beadfurther away from the nearest adjacent media edge, than at otherlocations.

The sealant bead modifications at both ends 413, 414 can be made with acontinuous process of sealant bead application, with gradual movement ofthe sealant bead with respect to its distance from the nearest edge.

The techniques described in connection with FIG. 21, can be applied witha variety of z-filter media arrangements. Preferred arrangements will beones which have urethane sealant as both the front side sealant bead andthe back side sealant bead, in accord with the descriptions herein.However, alternate seal arrangements are possible.

In general, then, methods of preparing a z-filter media constructionincluding coiled z-filter media are provided including steps accordingto the processes of FIGS. 11 and 21. The typical process comprises usingz-filter media comprising a fluted, and preferably corrugated, sheetsecured to a non-fluted non-corrugated facing sheet. The methodgenerally includes steps of: (a) guiding a front end extension of astrip of z-filter media into a media catch slot of a winding hub; (b) infollow up, coiling the strip of media around the outside of the windinghub, with the facing sheet directed outwardly, to form a resulting mediacoil; and (c) removing the resulting media coil from the winding hub.The method typically includes extending the media at least 0.75 inchinto the catch slot, preferably at least 1.0 inch.

Preferably the winding includes at least 6 coils, or involves windingaround at least 6 times, more preferably at least 10 times.

The step of winding can be conducted by rotating the hub, if desired.

Preferably the winding is conducted using a strip that has both a frontside sealant strip and a backside sealant strip, most preferably atleast the backside sealant strip is a foamed polyurethane.

After the resulting coil has been removed from the winding hub, it canbe distorted to an obround configuration, preferably with no addedcenter piece retained with the media during filtering. The obroundconfiguration is preferably racetrack shape. In some instances it may bedistorted to a racetrack shape having interdigitated flutes. In otherinstances, a temporary center piece can be positioned within a centeropening of the resulting coil, prior to distortion. After the step ofdistortion, the temporary center piece can be removed, so that aracetrack shaped obround filter element not having interdigitated flutesat least adjacent the backside sealant bead, and having no added centerpiece results.

According to the present disclosure, coiled z-filter media constructionsmade in accord with the various processes and techniques describedherein, are defined and preferred.

It is noted that as characterized herein with respect to FIGS. 12-16,along center strip of a racetrack shape having no added center piece,there is provided a first turn between two relatively straight strips,512, 514 (FIGS. 13 and 14) of corrugated media. Typically at this turn,three corrugations are used to make the turn, although alternatives arepossible. It has been observed that three corrugations can fit together,due to their shapes, to provide for a preferred turn.

It will be understood that the techniques or principles and examplesprovided, can be provided and used in a variety of specific manners, toaccomplish the desired results. The drawings and descriptions areintended to be exemplary only.

What is claimed is:
 1. An air filter cartridge comprising: (a) a filtermedia construction comprising a coiled configuration of fluted filtermedia secured to facing media; (i) the media construction having a shapewith two, opposite, generally parallel, sides joined by curved endportions; and, (ii) the filter media construction having a straightcenter strip at least 6 cm long extending generally parallel to the two,opposite, generally parallel sides; (b) a housing seal comprising aframework positioned surrounding the media construction and having ahousing seal member thereon; (i) the housing seal member having firstand second, opposite, straight, sides, one each in overlap with arespective one of the two generally parallel, opposite, sides of thefilter media construction; (ii) the housing seal member having at leasttwo, straight, sections each extending non-parallel to, andnon-perpendicular to, the straight center strip of the filter mediaconstruction; and, (iii) the housing seal member comprisingpolyurethane; and, (c) the center strip having at least sixinterdigitized flutes.
 2. An air filter cartridge according to claim 1wherein: (a) the filter media construction includes opposite flow faces;and, (b) the framework includes a portion extending across one of theflow faces.
 3. An air filter cartridge according to claim 1 wherein: (a)the center strip comprises at least 15 interdigitized flutes.
 4. An airfilter cartridge according to claim 1 wherein: (a) the center of thefilter media construction is closed by a sealant that increased involume at least 40% during cure.
 5. An air filter cartridge according toclaim 4 wherein: (a) the center of the filter media construction isclosed by polyurethane.
 6. An air filter cartridge according to claim 1wherein: (a) the housing seal member has at least one straight perimetersections extending perpendicular to the center strip.
 7. An air filtercartridge according to claim 6 wherein: (a) the housing seal member hasat least two straight perimeter section extending perpendicular to thestraight center strip.
 8. An air filter cartridge according to claim 1wherein: (a) the filter media construction includes opposite, parallel,flow faces; and, (b) the framework includes a portion extending acrossone of the flow faces.
 9. An air filter cartridge comprising: (a) afilter media construction comprising a coiled configuration of flutedfilter media secured to facing media; (i) the media construction havinga shape with two, opposite, generally parallel, sides joined by curvedend portions; and, (ii) the filter media construction having a straightcenter strip at least 6 cm long extending generally parallel to the two,opposite, generally parallel sides; (b) a housing seal comprising aframework positioned surrounding the media construction and having ahousing seal member thereon; (i) the housing seal member having firstand second, opposite, straight, sides, one each in overlap with arespective one of the two generally parallel, opposite, sides of thefilter media construction; and, (ii) the housing seal member having atleast two, straight, sections each extending non-parallel to, andnon-perpendicular to, the straight center strip of the filter mediaconstruction; (c) the filter media construction including opposite,parallel, flow faces; (d) the framework including a portion extendingacross one of the flow faces; and, (e) the center of the filter mediaconstruction being closed by a sealant that increased in volume at least40% during cure.
 10. An air filter cartridge according to claim 9wherein: (a) the center of the filter media continuation is closed bypolyurethane.